[sdiy] Square to Sine

[Andrew Simper]

Great! Forgot to say you'll need a dc blocker somewhere down the line
as the BJT has a diode drop from base to emitter.

What do you want a "dirty" fixed frequency sin for?

Andy

On 5 April 2017 at 12:10, Elain Klopke <functionofform at gmail.com> wrote:
> Thanks Andy! I still had my resistors and caps on my breadboard and hooked
> up a 2N3904 and plugged in the power and the Tiny Speaker Test agrees that
> it works decently.
>
> On Tue, Apr 4, 2017 at 9:41 PM, Andrew Simper <andy at cytomic.com> wrote:
>>
>> One way to avoid some of the volume drop is to use a 2 pole sallen key
>> BJT filter with a cascaded passive stage. This is a common circuit
>> used around BBD chips, eg:
>>
>>
>> http://www.hobby-hour.com/electronics/s/schematics/boss-ce2-chorus-schematic.gif
>>
>> Andy
>>
>> On 4 April 2017 at 19:50, Elaine Klopke <functionofform at gmail.com> wrote:
>> > Thanks for the info Tom!
>> >
>> > Magnus, the sources are fixed square waves coming from a set of PIC
>> > chips. So the fixed filtering doesn't bother me a bit. One filter for one
>> > frequency. What worries me is the volume drop.
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>
>